X-ray radiation is widely used in many areas including medical diagnostics and treatment, industrial inspection and testing, security screening and detections. Current x-ray sources are mostly based on a thermionic cathode to generate electron beam, which is accelerated to high energy to bombard a metal target to generate x-ray. Thermionic cathode based x-ray sources cannot be easily switched on/off rapidly and the x-ray flux cannot be easily controlled due to the slow response of thermal process and the nonlinear relationship between the cathode current and the electron beam current. At the same time, the hot filament based x-ray tube is generally bulky due to the heating and insulation parts required for the filament heating. It is in principle difficult to integrate multiple x-ray units together to form an integrated multi-beam x-ray source which can provide multiple x-ray beams simultaneously.
Recently, x-ray generating devices and methods based on nanostructure containing field emission cathodes have been developed. Examples of such x-ray generating devices and methods are described in U.S. Pat. Nos. 6,553,096, 6,850,595, and 6,876,724. These devices and methods provide several advantages over conventional hot filament based x-ray tubes. Firstly, the field emission x-ray (FEX) source can be easily triggered to generate x-ray pulse in arbitrary temporal waveform. This feature can enable new radiography imaging techniques that are not possible (or practical) with conventional x-ray sources. Secondly, the field emission x-ray source operates at room temperature, which is much lower than conventional hot filament based x-ray tubes. Further, because there is no heat, it is free of bulky insulation or ventilation components, so such a device is much smaller than conventional machines.
It would be beneficial to provide x-ray radiography systems and methods having reduced data collection times, enhanced signal-to-noise ratios, and better x-ray source power distribution. One or more such improvements can enable new x-ray imaging and x-ray analysis applications. Accordingly, it is desirable to provide x-ray radiography systems and methods having one or more of these improvements.